feat(matrixbot): stop auto-joining invites, restrict commands to two rooms

#general is now published to the public room directory, so the bot is
reachable by strangers. Two hardening changes:

- Invites are only accepted from INVITE_ALLOWED_USERS (defaults to
  ADMIN_USERS). Anything else is declined via room_leave so hostile
  invites do not accumulate as pending. Previously any invite from
  anyone was auto-joined.
- Commands and the passive scramble/riddle answer checks only run in
  COMMAND_ROOMS (#commands and #management). The gate sits early in
  Callbacks.message, so the bot stays silent everywhere else, including
  #general. Set COMMAND_ROOMS="*" to restore the old behaviour.

Reaction handlers are deliberately left ungated so the welcome flow
keeps working; game votes elsewhere cannot match an active game.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

matrixbot/bot.py

@@ -21,6 +21,7 @@ from config import (
     MATRIX_ACCESS_TOKEN,
     MATRIX_DEVICE_ID,
     MATRIX_PASSWORD,
+    INVITE_ALLOWED_USERS,
     LOG_LEVEL,
     ConfigValidator,
 )
@@ -148,13 +149,21 @@ async def main():
     client.add_event_callback(callbacks.unknown_event, UnknownEvent)
     client.add_event_callback(callbacks.member, RoomMemberEvent)
 
-    # Auto-accept room invites
+    # Accept invites only from trusted users, and decline the rest so they do
-    async def _auto_accept_invite(room, event):
+    # not sit pending forever. Never auto-join on an arbitrary invite.
-        if event.membership == "invite" and event.state_key == MATRIX_USER_ID:
+    async def _handle_invite(room, event):
-            logger.info("Auto-accepting invite to %s", room.room_id)
+        if event.membership != "invite" or event.state_key != MATRIX_USER_ID:
+            return
+        if event.sender not in INVITE_ALLOWED_USERS:
+            logger.warning(
+                "Declining invite to %s from untrusted sender %s", room.room_id, event.sender
+            )
+            await client.room_leave(room.room_id)
+            return
+        logger.info("Accepting invite to %s from %s", room.room_id, event.sender)
         await client.join(room.room_id)
 
-    client.add_event_callback(_auto_accept_invite, InviteMemberEvent)
+    client.add_event_callback(_handle_invite, InviteMemberEvent)
 
     # Graceful shutdown
     loop = asyncio.get_running_loop()

matrixbot/callbacks.py

@@ -3,7 +3,7 @@ from functools import wraps
 
 from nio import AsyncClient
 
-from config import BOT_PREFIX, MATRIX_USER_ID
+from config import BOT_PREFIX, COMMAND_ROOMS, MATRIX_USER_ID
 from commands import (
     COMMANDS,
     metrics,
@@ -50,6 +50,12 @@ class Callbacks:
         if event.sender == MATRIX_USER_ID:
             return
 
+        # Only act in designated command rooms. This covers both prefixed
+        # commands and the passive game-answer checks below, so the bot never
+        # speaks in public rooms such as #general. "*" allows every room.
+        if "*" not in COMMAND_ROOMS and room.room_id not in COMMAND_ROOMS:
+            return
+
         body = event.body.strip() if event.body else ""
 
         # Check active non-command games that monitor all room messages

matrixbot/config.py

@@ -16,12 +16,28 @@ BOT_PREFIX = os.getenv("BOT_PREFIX", "!")
 ADMIN_USERS = [u.strip() for u in os.getenv("ADMIN_USERS", "").split(",") if u.strip()]
 LOG_LEVEL = os.getenv("LOG_LEVEL", "INFO")
 
+# Rooms where commands and interactive games are allowed. The bot stays silent
+# everywhere else, so it never responds in public rooms like #general.
+# Override with a comma-separated COMMAND_ROOMS; set to "*" to allow all rooms.
+DEFAULT_COMMAND_ROOMS = (
+    "!ou56mVZQ8ZB7AhDYPmBV5_BR28WMZ4x5zwZkPCqjq1s",  # #commands
+    "!mEvR5fe3jMmzwd-FwNygD72OY_yu8H3UP_N-57oK7MI",  # #management
+)
+_command_rooms = os.getenv("COMMAND_ROOMS", ",".join(DEFAULT_COMMAND_ROOMS))
+COMMAND_ROOMS = [r.strip() for r in _command_rooms.split(",") if r.strip()]
+
+# Users whose invites the bot will accept. Invites from anyone else are
+# declined: the homeserver is publicly listed, so auto-joining any invite lets
+# a stranger pull the bot into an arbitrary room. Defaults to ADMIN_USERS.
+_invite_allowed = os.getenv("INVITE_ALLOWED_USERS", "")
+INVITE_ALLOWED_USERS = [u.strip() for u in _invite_allowed.split(",") if u.strip()] or list(ADMIN_USERS)
+
 # Integrations
 OLLAMA_URL = os.getenv("OLLAMA_URL", "http://10.10.10.157:11434")
 OLLAMA_MODEL = os.getenv("OLLAMA_MODEL", "phi4-mini:latest")
 CREATIVE_MODEL = os.getenv("CREATIVE_MODEL", "huihui_ai/llama3.2-abliterate:3b")
 ASK_MODEL = os.getenv("ASK_MODEL", "phi4-mini:latest")
-MINECRAFT_RCON_HOST = os.getenv("MINECRAFT_RCON_HOST", "10.10.10.67")
+MINECRAFT_RCON_HOST = os.getenv("MINECRAFT_RCON_HOST", "10.10.10.68")
 MINECRAFT_RCON_PORT = int(os.getenv("MINECRAFT_RCON_PORT", "25575"))
 MINECRAFT_RCON_PASSWORD = os.getenv("MINECRAFT_RCON_PASSWORD", "")